Electrolytic rectifier



March 6, 1928.

C.E.QGDEN ELEcTRoLYc RECTIFIER Filed Aug. 6. 1926 ldatented Mar. 6, 1928.

UNITED STATES PATENT OFFICE..

CLARENCE E. OGDEN, OF CNGINNAT-I, OHIG, ASSIGNOR TO THE KDEL RADIO COR- PORATION, A CORPORATON @F OHIG.

ELECTROLYTIC RECTIFIER.

Application tiled August 6, 1926.

The present invention relates to electro- -lytic rectitiers. l

The principal object of the present invention is to provide an electrolytic rectier adapted particularly for battery charging in which the life ot the rectiliying electrode is prolonged so that replacements and repairs are reduced to a minimum.

A further object is to provide in an electrolytic rectifier an electrolyte wherein the necessity vfor the frequent additions ot liquid as, tor instance, distilled water, is obviated.

A further object of the invention is to provide in an electrolytic rectifier having a cathode of silicon or silicon alloy in an acid electrolyte, by the use of which the life of the electrode is prolonged indefinitely. ln the drawing the' ligure is aseCtiOnal view of an electrolytic rectifier constructed in accordance with this invention.

In electrolytic rectitiers wherein acid is employed as an electrolyte and silicon or a silicon alloy is used for the rectiifying electrodc, l have found that where-the surface ot the electrode is not smooth, but is permeated with sand holes or depressions causing numerous sharp points or inequalities in the electrode surface, by the employment of the ordinary acid, that is sulphuric acid of approximately 1250 specific gravity, the electrode is attached at said points and a'l'ter a comparatively short period of use the electrode is worn through and breaks, thus requiring replacement before the rectifier can again he used. This dilliculty is not experienced where the surface of the electrode is smooth. The fault is caused, according to my observation, not by reason of the acid attacking the metal, but because of the brealting ot the rectitying film at the numerous sharp points on the surface of the electrode, thus permitting the current to burn and disintegrate the metal, resulting` in ultimate fracture. By the use of an electrolyte of a considerable degree of viscosity, however, l have found that the rectitying film is appar- Serial No. 127,707.

ently of increased tensibility so that the sameV is not fractured at or by the points on the surface of the electrode, and the metal is thus protected from the disintegrating effect of the passage ot current at such points, and rapid deterioration of the electrode is obviated.

In carrying out the present invention I have found that the desired viscosity may be obtained either by -the addition of a liquid of approximately the same specific gravity as the electrolyte as, tor instance, glycerine, or by the preferred method of employing an acid electrolyte of high specific gravity; that is, sulphuric acid of not less than 1300 specic gravity, such high gravity acid being of viscous consistency.

By numeroustests and experiments over a long period of time, I have found that the use kot high gravity acid permits the use of electrodes of the character mentioned whether the same arev snperficially smooth or rough, there being apparently no diference in the durability of the respective elec, trodes 1n such acid, whereas whenacid of.

low speciiic gravity is used in accordance with the practice heretofore obtaining, while the lower resistance gives a slightly greater ioiv ot current, the electrodes unless approximately. smooth are practically valueless for the reason that they must be replaced at extremely short intervals by reason of the disintegration above mentioned. Furthermore, where high gravity acid is used it will loe understood that the lack of Water in the acid results in a much slower disintegration of the electrolyte and there fore requires less frequent additions thereto.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

ln an electrolytic rectilier, in combination with an electrode containing silicon, an acid electrolyte comprising sulphuric acid of from 9U 

